The considerable potential of central immune cytokine interleukins such as IL-2 and IL-4 for cancer treatment has sparked numerous efforts to improve their therapeutic properties by mutation and/or chemical modification. However, because these approaches are closely tied to native IL-2 or IL-4, they cannot eliminate undesirable properties such as low stability and binding to the IL-2 receptor a subunit (IL-2Rα), to IL-4 receptor αγc heterodimer (IL-4Rαγc), or to IL-13 receptor α subunit (IL-13Rα).